From airplanes weighing hundreds of tons to drones weighing thousands of grams, many people may think that lighter things are easier to fly. In fact, when the weight of an aircraft is less than 10 grams, its flight time generally does not exceed 10 minutes. The flight duration and power issues of micro robots are a difficult problem facing researchers. On May 8th, a research result by Professor Yan Xiaojun's team from the School of Energy and Power Engineering at Beihang University was published in a sub journal of Nature. The team has invented a micro power system for insect robots, and based on this, developed a fast maneuvering, high load, wireless controllable micro robotic insect. Two months later, another research achievement by the team on micro air vehicles was published online in the main journal of Nature on July 18th, and was recommended on the homepage of both the top journals of Nature and Science. This small creature weighing only 4.21 grams is currently the lightest and smallest pure natural light powered micro aircraft in the world, called the electrostatic aircraft "CoulombFly". Even the smallest aircraft, lighter than an A4 sheet of paper, must have an engine to provide sufficient power to fly. The contradiction facing researchers is that currently, the engine driving components of micro air vehicles generally use traditional electromagnetic motors. However, after miniaturization, electromagnetic motors have high rotational speed and generate large amounts of heat, resulting in a sharp decrease in energy conversion efficiency, even to below 10%. After the efficiency of the micro electromagnetic motor decreases, if natural light, which is convenient for power supply, is used as the energy source, due to the limited area of the solar cell, it is difficult to meet the flight requirements, and the aircraft cannot fly. Nowadays, the electrostatic aircraft independently developed by the Beihang team has a wingspan of 20 centimeters, weighs 4.21 grams, and is only the size of a palm, lighter than an A4 sheet of paper. This research achievement was independently developed by the research team of Beihang University, which will significantly increase the flight time of micro air vehicles and expand their application scope. At the same time, another micro power system developed by Yan Xiaojun's team for insect robots can be used for bionic machines called "insects". This insect robot achieves fast maneuverability, high payload capacity, and wireless controllability, and can be applied in post disaster rescue, large-scale mechanical equipment maintenance, and other scenarios. Whether it is insect robots or micro air vehicles, the initial concept originated from a slightly vibrating thin beam. Placing a beam in an electrostatic field environment, which is extremely fine with a diameter of only about twenty micrometers, will cause the beam to vibrate like a strand of hair in the electrostatic field, which is the phenomenon of micro beam electrostatic vibration. I am a researcher of motivation. In 2009, after discovering this phenomenon in the laboratory, I wanted to use it to do something Yan Xiaojun explained to the reporter from China Youth Daily and China Youth Network. Starting from this vibrating micro beam, Yan Xiaojun quickly thought to himself, 'The principle of insect flight is also a kind of vibration.'. The phenomenon of electrostatic vibration in micro beams may become a solution for the power and propulsion of micro air vehicles, from a micro beam to a robot that can ultimately fly. Yan Xiaojun began to explore the possibility of applying the micro beam flutter mechanism to fields such as micro air vehicles or micro insect robots. His doctoral students at that time, Qi Mingjing and Liu Zhiwei, successively turned to this direction and conducted research around this phenomenon. After graduating, Dr. Qi Mingjing stayed at the school to teach and continued to conduct relevant research in Yan Xiaojun's team. Afterwards, with the joint efforts of two doctoral students, Shenwei, who developed electrostatic motors, and Peng Jinzhe, who developed boost systems, the team made breakthrough progress. Shen Wei is a doctoral student of Qi Mingjing. In the laboratory of the School of Energy and Power Engineering at Beihang University, he demonstrated an electrostatic motor that can take off to reporters from China Youth Daily and China Youth Net. In the small buzzing sound, a palm sized micro aircraft gently flew up. It is this type of micro air vehicle based on the principle of electrostatic motors that has appeared on the homepage of the official websites of both Nature and Science. From crawling to takeoff, Dr. Zhan Wencheng, a member of the team at Beihang University, also presented the latest achievements of the team to reporters from China Youth Daily and China Youth Net. The "beetle" with a black shell doesn't look as big as a mineral water bottle cap. In complex miniature terrain tests, the small insect robot demonstrates amazing flexibility and adaptability, with four slender legs swinging flexibly and shuttling back and forth between obstacles, like a real beetle. According to Zhan Wencheng, insect robots are implanted with energy, control, communication, and sensing systems, which can accurately identify and avoid obstacles through precise sensors and intelligent algorithms, and perform detection tasks. The team also designed a biomimetic running gait that allows this mechanical beetle to adaptively adjust its step frequency and stride, enabling it to crawl quickly even under high loads. There is a significant breakthrough in its load-bearing capacity. Its self weight is 0.3 grams, and it can crawl approximately 40 centimeters per second while carrying a weight of 2 grams Zhan Wencheng said. At present, our most complex system is a visual sensing system, weighing approximately 1.5 grams. Behind every subtle movement of this carbon fiber "beetle", the team has accumulated 15 years of hard work in microelectromechanical systems, artificial intelligence algorithms, and biomimetic design. From the earliest mechanism research, to gradually expanding to the study of drivers, and then gradually expanding to the whole machine. This research spans across multiple disciplines such as mechanics, electronics, control science, and robotics, and faced challenges in the early stages due to a lack of equipment and experience. In Yan Xiaojun's words, this process can be described as a "blue thread on the road". We originally designed insect robots with the intention of making them fly. However, currently, if micro robots use high-capacity batteries, their weight is too heavy to fly; If a small capacity battery is used, it cannot provide enough energy to make it fly, so it is eventually turned into a crawling one Yan Xiaojun said with a hint of regret. In order to enable the "beetle" to fly, Yan Xiaojun and other members of the team gathered relevant literature on biology and carefully studied it; We have also gathered some insect documentaries, including bees, dragonflies, etc., to study the posture and trajectory of insect flight frame by frame. They even bought bees and observed how their wings flap in the laboratory. As for bees, our main task is to collect the vibration parameters of their wings, such as the maximum angle at which the wings swing back and forth, which is usually 120 degrees. And its oscillation frequency is about 200 hertz per second. Its wings not only vibrate, but also twist, and we also count its twist angle, which is about 45 degrees Zhan Wencheng said. However, despite the team's best efforts, the replicated wings still failed to achieve the same level of lift as bee wings. Some members were accidentally stung by bees Yan Xiaojun smiled bitterly and said, "At first, we thought there was a problem with the trajectory of the wing vibration. After studying the insect documentary, the trajectory was done correctly, but the lift was still not enough. We are now stuck in this link. We have already used circuits and the like to the extreme, and they are very small." Despite not being able to fly, the team's "beetle" still achieved a major breakthrough in the field of micro robots. Traditional micro robots have insufficient internal space to carry high-capacity batteries and must be continuously powered by an external power source, making it impossible for them to move freely. The research team of Beihang University has developed a new power system based on linear drive and flexible hinge transmission. The "Beetle" has freed itself from tail like wires and can run freely for 10 minutes every 2 minutes of charging. On the road of research, the team kept trying and making mistakes and never gave up their dream of making insect robots fly. The entire research group was divided into several different groups, each studying different technical solutions to seek the optimal engineering solution. Team member and associate professor of Beihang University, Liu Zhiwei, led doctoral student Zhan Wencheng to continue researching insect robots, while Qi Mingjing turned to research in the field of electrostatic motors. In our school, every student may have some longing for flying, but it's really difficult to develop their own flying system. We have tried many driving methods, but they are all quite difficult. Finally, we attempted to construct an electrostatic motor, which did not oscillate back and forth like a micro beam, but rather rotated. In this way, the power output is not limited Shenwei explained. It is reported that micro air vehicles are small in size, lightweight, and highly maneuverable, capable of performing special tasks such as photography, detection, and transportation in narrow spaces, and have broad application prospects in the field of national economy. In order to solve the challenges of driving and endurance, the team sought breakthroughs in the principle of micro engines, proposed a new electrostatic driving scheme, developed a micro electrostatic motor with low speed, low heat generation, and high efficiency at a small size, and successfully flew an electrostatic aircraft. The concept of electrostatic motors has existed for hundreds of years, even earlier than battery motors, but it has not been fully utilized and its theoretical direction is also somewhat deviated. After our improvement and reconstruction, its output power has been greatly increased, enabling it to fly Shen Wei said. It is reported that this new type of micro air vehicle is mainly composed of an electrostatic engine and an ultra lightweight high-voltage power supply, with the advantages of low power consumption of 0.568 watts and high lift of 30.7 grams per watt, achieving for the first time the takeoff and continuous flight of micro air vehicles under pure natural light power supply. Despite breakthroughs in the direction of electrostatic motors, Yan Xiaojun told reporters that the team will still not give up on making the "beetle" fly. We are still exploring various technological solutions, including increasing the vibration frequency, changing the driving scheme, etc., and we will not give up Yan Xiaojun mentioned that his mentor Professor Nie Jingxu devoted himself to the aviation industry with a passion for "serving the country through the sky and space", and was "particularly persistent" in his research. Every time he proposed a plan, it was "very clever and full of wisdom". This persistent spirit has inspired generations of Beihang people and ignited their interest in scientific research. In Yan Xiaojun's opinion, these doctoral students in the team now also have the same enthusiasm and persistence. To pursue the path of engine development, one needs to have a passionate heart, persist in trial and error, and eventually succeed He said. (New Society)